The 24-year-old man needed CPR on the beach after being pulled out of Sasamat Lake in Port Moody on Sunday afternoon, said a statement by the Port Moody Police Department on Monday.
The victim, who has not been named, was airlifted to hospital, but passed away on Sunday night, the statement added.
Two other men drowned in separate incidents on Saturday.
A 19-year-old man drowned in the Similkameen River in the south Okanagan after falling from his raft and being swept away by strong currents.
And a 21-year-old international student died after suddenly finding himself over his head while swimming in Thetis Lake, northwest of Victoria.
The run of hot weather across British Columbia may be partly to blame for a spike in drownings in the province this summer, according to officials from the Lifesaving Society of B.C. and Yukon.
Most victims are young men trying risky activities like cliff jumping, or the victims simply don't expect to end up in deep water, they say.